Psychologists say that depression is rage turned inward. Stand-up comedy, on the other hand, is rage turned back outward again. (I believe George Carlin had a routine about the use of violent metaphors directed at the audience in comedy: "Knock 'em dead!" "I killed!") In the documentary "Heckler" (now on Showtime and DVD) comedian Jamie Kennedy, as himself, plays both roles with ferocious intensity. The movie is his revenge fantasy against anyone who has ever heckled him on stage, or written a negative review... or, perhaps, slighted him in on the playground or at a party or over the phone or online.

"Heckler" (I accidentally called it "Harangue" just now) is an 80-minute howl of fury and anguish in which Kennedy and a host of other well-known and not-well-known showbiz people tell oft-told tales of triumphant comebacks and humiliating disasters, freely venting their spleens at those who have spoken unkindly of them. At first the bile is aimed at hecklers in club audiences (with some particularly nasty invective for loudmouthed drunken women), then it shifts to "critics" -- broadly defined as anybody who says something negative about a figure whose work appears before a paying public. Some of the critics are actually interested in analysis; some are just insult comics who are using the Internet as their open mic. It gets pretty ugly, but it's fascinating -- because the comics, the critics and the hecklers are so much alike that it's no wonder each finds the others so infuriating.